It is well-known that Lead-contained copper alloy is an important basic material which are widely used in machine-made industry such as drinking-water installations, in particular for the manufacture of fittings, connecting castings and its spares which continuously contact with drinking water for human consumption. In recent years the experts of medicine in various countries have discovered that the Pb-contained brass severely influence the health of human body, and is threatening the safety of the environment. The academy and research institutes of medicine in north Europe, America, Japan, and China have been reporting the concerns focused on Pb-containing brass threatening the human environment in recent years.
Ingestion of lead by humans is harmful, therefore the use of lead is being strictly banned due to the concerns on health and environment. Drinking water is one such concern and legislation has been proposed to reduce the concentration of lead in particular in connection with drinking-water system, plumbing fixtures and fittings and thus to reduce the amount of lead leached into the water. Accordingly, there have been attempts to reduce the lead content of alloys and numerous elements have been proposed as substitutes for lead.
Chinese Pat. No. 02121991.5 discloses one such alloy invented by Mitsukoshi Ltd. of Japan that contains 60.0 to 62.0% Cu, 0.5 to 2.2% Bi, 0.01 to 0.1% Al, 0.5 to 1.6% Sn, 0.04 to 0.15% P and the balance Zn with unavoidable impurities. The alloy is annealed for 30 minutes to 4 hours in a range from 460° C. to 600° C., and then cooled with a speed under 70° C./h. It is a lead-free Cu—Zn—Bi alloy, because within which Bi is an element, however, Bi increases the production cost, and its resource in the global is exhaustible, therefore, the lead-free free-cutting alloy containing bismuth is not a competitive product.